Research on Control Strategy for Improving High Voltage Ride Through Ability of Permanent Magnet Direct Drive Wind Turbine

In the study, the DC bus voltage is increased combined with the energy storage device to improve the high voltage fault ride through capability of the direct drive unit. The relationship between DC bus voltage, grid voltage and grid-connected power during the fault is analyzed, and the function relationship between the given value of DC bus voltage and grid voltage and maximum output current is derived. When a deep high voltage fault happens in power grid with continuous high voltage fault, long fault duration and large sudden rise, the DC bus voltage is increased to maximum allowable value, as well as wind power is output as much as possible. The remaining power is absorbed by the super capacitor energy storage device. This method can effectively improve the active power output capacity of grid-side converter, lower the capacity configuration of super capacitor and grid-side converter, save the investment cost of system hardware, and effectively improve the fault ride through capability of system. Combined with system model, the voltage loop auto disturbance rejection control (ADRC) is designed. In comparison with traditional PI controller, after the system fault is removed, the system can recover quickly and achieve better control performance. In the end, this efficacy of the suggested control strategy is proved by simulating.